1.46 coherent derived unit Derived unit that, for a given system of quantities and for a chosen set of base units, is a product of powers of base units with no other proportionality factor than one. Note 1: A power of a base unit is the base unit raised to an exponent. Note 2: Coherence can be determined only with respect to a particular system of quantities and a given set of base units. Examples: If the metre, the second, and the mole are base units, the metre per second is the coherent derived unit of velocity when velocity, v, is defined by the quantity equation v = dr/dt where r denotes distance and t time, and the mole per cubic metre is the coherent derived unit of amount-of-substance concentration when amount-of-substance concentration, c, is defined by the quantity equation c = n/V where n denotes amount of substance and V volume. The kilometre per hour and the knot are examples of derived units which are not coherent derived units in the International System of Quantities. Note 3: A derived unit can be coherent with respect to one system of quantities, but not to another. Example: The centimetre per second is the coherent derived unit of speed in the CGS system of units but is not a coherent derived unit in the SI. Note 4: The coherent derived unit for every derived quantity of dimension one in a given system of units is the number one, symbol 1. The name and symbol of the measurement unit one are generally not indicated. Source: [VIM 1.12].
 1.46 coherent derived unit Derived unit that, for a given system of quantities and for a chosen set of base units, is a product of powers of base units with no other proportionality factor than one. Note 1: A power of a base unit is the base unit raised to an exponent. Note 2: Coherence can be determined only with respect to a particular system of quantities and a given set of base units. Examples: If the metre, the second, and the mole are base units, the metre per second is the coherent derived unit of velocity when velocity, v, is defined by the quantity equation v = dr/dt where r denotes distance and t time, and the mole per cubic metre is the coherent derived unit of amount-of-substance concentration when amount-of-substance concentration, c, is defined by the quantity equation c = n/V where n denotes amount of substance and V volume. The kilometre per hour and the knot are examples of derived units which are not coherent derived units in the International System of Quantities. Note 3: A derived unit can be coherent with respect to one system of quantities, but not to another. Example: The centimetre per second is the coherent derived unit of speed in the CGS system of units but is not a coherent derived unit in the SI. Note 4: The coherent derived unit for every derived quantity of dimension one in a given system of units is the number one, symbol 1. The name and symbol of the measurement unit one are generally not indicated. Source: [VIM 1.12].

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